AT&T will introduce high-definition voice on its all-IP, Voice over LTE (VoLTE) network in a handful of markets on May 23. The carrier says it’s similar to upgrading from standard-definition television to HDTV.

HD voice customers will be able to talk while surfing the Web at LTE speeds at the same time. But to take advantage of it, both the caller and the receiver must have compatible handsets.

At rollout, HD voice will only be available on one device: the Samsung Galaxy S4 mini. AT&T promises more HD voice-compatible phones are on their way.

The first areas to get the new technology are parts of Minnesota, Illinois, Indiana and Wisconsin.